(UNDATED) - An Indiana University medical ethicist is defending a controversial Facebook research study.

IU Center for Bioethics Director Dr. Eric Meslin says the study - published in the journal Nature - combines marketing, science and social media for the purpose of public education. However, the study got widespread, angry criticism from Facebook users who claimed their privacy had been breached and Facebook and Cornell University should've been more transparent about the study during its progress.

The study randomly selected 310,000 users and altered their news feeds to measure for written reactions to positive and negative comments.

Meslin, along with four other IU faculty members, say the study was ultimately public, not harmful and the results were published. In short, Meslin says Facebook and Cornell University operated in an ethical manner and society needs these sorts of studies to gain greater insight into human behavior.

Meslin says it's "ethically inconsistent" for people to put much of their personal lives onto public platforms and then somehow expect complete privacy at all times.